Saint John Bosco

Fly from bad companions as from the bite of a poisonous snake. If you keep good companions, I can assure you that you will one day rejoice with the blessed in Heaven; whereas if you keep with those who are bad, you will become bad yourself, and you will be in danger of losing your soul. 

-- Saint John Bosco

Saint Justin Martyr

I have endeavored to learn all doctrines; but I have acquiesced at last in the true doctrines, those namely of the Christians, even though they do not please those who hold false opinions.

-- Saint Justin Martyr at his trial

Saint Vincent de Paul

It was His Will that after His death the Church should give us His image in the crucifix, that he might appear to us in a condition of utmost ignominy. And why? He did it because He knew the worth of humility and the danger of the sin which opposes it.

-- Saint Vincent de Paul